Gilmour is set to face Dundee this weekend at Dens Park.
The central midfielder joined Arsenal at the age of six and went on to make two Europa League appearances in 2018.
He would leave for Norwich in 2019 and spent a season on loan at Telstar in the Dutch second-tier before St Johnstone snapped him up on a short-term deal in February 2021.
A two-year contract then followed but Gilmour has only made 12 appearances for Saints and went out on a season-long loan at Cove this term.
He has played 17 times for Jim McIntyre’s outfit, playing 90 minutes as the Aberdeen side defeated Dundee 3-1 in October.